EP1693331A1 discloses an elevator system with vertical tracks which are formed by two car guide rails in each case, in which the vertical tracks extend between a lowermost stopping station and an uppermost stopping station and are each equipped with at least one separately controllable drive system. Each drive system comprises a flexible supporting means extending over the entire length of the vertical tracks. This elevator system also includes a plurality of elevator cars which are movable and stoppable upward along the first vertical track and downward along the second vertical track by means of the drive systems. In this case, each elevator car has a controllable coupling mechanism with which said elevator car can be coupled in an interlocking manner to the supporting means of a drive system assigned to the present vertical track thereof. An upper and a lower car transfer mechanism have the task of taking over elevator cars which have arrived in the end regions of the vertical tracks and of displacing said elevator cars horizontally to the other vertical track where the elevator cars are introduced into the guide rails of the other vertical track.
In an elevator system designed in accordance with the teaching disclosed in EP1693331A1, all of the elevator cars are equipped with in each case four upper and four lower car supporting rollers which are mounted on pivotable supporting structures in order to permit horizontal displacement of said elevator cars between two vertical tracks. When an elevator car has reached the uppermost position thereof, the four upper car supporting rollers thereof are pivoted, for the horizontal displacement, into a profile rail, which is arranged horizontally above the vertical tracks, such that the elevator car is supported and guided by the profile rail and the car supporting rollers. After an elevator car has arrived in the lowermost position thereof, the lower car supporting rollers thereof are pivoted into a profile rail, which is arranged horizontally below the vertical tracks, so that the elevator car is displaceable horizontally on said lower profile rail. In addition, in both end positions, a drive device (not illustrated in the drawing) is required to produce the horizontal movement of the elevator cars. Similarly, in order to permit the horizontal displacement of the elevator cars, in the case of the disclosed elevator system having two vertical tracks, a total of eight end sections of car guide rails are arranged pivotably and are provided with controllable pivoting drives. When said end sections are pivoted back into the guide positions thereof, the end sections have to be introduced again into the guide grooves, which have little play, of the guide shoes which are present on the elevator car which is not highly dimensionally stable. For an additional vertical track, the number of car guide rails which can be pivoted away would be increased by eight.